Suggestions on turning eccentric

Discussion in '400-Day & Atmos' started by KurtinSA, Jan 27, 2020.

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  1. KurtinSA

    KurtinSA Registered User
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    I've worked on a Kieninger & Obergfell large size clock. Finally have it cleaned up as well as my polishing hand can do. In looking at locks and drops, the exit drop is larger than the entrance...the locks are OK as far as I can tell. The book says I need to lower the pivot hole. This clock has eccentrics on both plates, but the anchor is near the rear plate.

    This is the picture I posted about the clock...this shows the back plate:

    https://mb.nawcc.org/attachments/koborgbck-jpg.551501/

    I think you can see the slot on the eccentric is plenty chewed up from past abuse. I've tried to use a few screwdrivers, etc., to turn the eccentric. It's not moving and there is the tendency for the tool to slip up and out of the slot...not good.

    How should I attack this?

    Thanks...Kurt
     
  2. Wayne A

    Wayne A Registered User
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    #2 Wayne A, Jan 27, 2020
    Last edited: Jan 27, 2020
    This is what I use, modified 90deg screw driver by filing the tip thinner also removing the taper in the blade that tends to push the blade out of the slot.
    I only use the tip on the right side of the pic.

    20200127_093744.jpg
     
  3. KurtinSA

    KurtinSA Registered User
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    Wayne -

    I also have one of those, however the thickness of the blade (yours and mine) is too small. I also have a cheap screwdriver with a larger thickness blade which I ground down to better fit the eccentric slot.

    But the picture hopefully shows how badly this slot is. The edges of the slot are already moved around making it hard for anything to stay put. In other situations when dealing with stuck fasteners on vintage vehicles, I read that using something like "valve grinding paste" helps the tool to better grip. Can't say as I've seen this type of paste around but haven't really looked either.

    Kurt

    KOEccentric.jpg
     
  4. Wayne A

    Wayne A Registered User
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    Slot does look bad but hard to determine scale. I like the angle screw drivers because of amount of leverage they offer. Maybe a drop or Kroil penetrating oil would help free it up.
    I've seen the valve lapping compound used, its a fine abrasive in a light grease base so probably would increase friction by digging into the brass and screwdriver blade.

    Valve lapping brings back memory's from the early 80's when I worked on analytical equipment in a gasoline "motor" lab. There were many octane engines there and the guy that maintained them spent hours every week lapping valves by hand with lapping compound. Can still see him spinning that tool like someone trying to start a fire with a stick.:)
     
  5. KurtinSA

    KurtinSA Registered User
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    As I've thought about it some more and gotten some input, I think I'm going to have to take the clock apart and put the back plate on some wooden blocks. I may have to get another sacrificial screwdriver, or I can try the large one that I have and lean onto the screwdriver to limit the slip of the blade in the slot. Maybe I can get the eccentric to turn. I have considered Kroil in case there's some corrosion. Beyond that, I guess the only thing to do is to replace the eccentric...out of my wheelhouse at the moment.

    Kurt
     
  6. sjaffe

    sjaffe Registered User

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    Kurt,
    You need to break this free, so when you insert the driver blade alternate applying torque clockwise and counterclockwise rather than just one direction.
    Stan
     
  7. Raymond Rice

    Raymond Rice Registered User
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    I recently faced a similar problem with a seized screw in a miniature steam engine. I tried every kind of solvent/snake oil that I have accumulated over the years. I was in no hurry, but over a period of weeks, no success/no joy. I then acquired something called "CRC Freeze Off" -- the theory is that the propellant subjects the target fastener to extreme cold, causing shrinkage which allows the penetrant to seep in. It took two applications, but it worked for me. Your mileage may vary.
    Ray Rice
     
  8. shutterbug

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    It should be very rare to have to adjust the eccentric. They are set at the factory, and that normally is the right position for them. If the clock won't run, it's probably something else causing the problem.
    The drops are important, but if the lock is good on both pallets, unequal drops won't affect it too much.
     
  9. KurtinSA

    KurtinSA Registered User
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    shutterbug -

    That's news to me that having the escapement not correct won't impact the way the clock runs. As for the location of the eccentric now, given how much the slot is chewed doesn't give me confidence the current setting. And seeing the vast difference in the drops suggest it needs adjustment.

    Kurt
     
  10. Wayne A

    Wayne A Registered User
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    Seems like the clocks that I find needing eccentric adjustment already had been adjusted. Working on a Koma now that had everything that could be adjusted moved out of operating range..
     
  11. Kevin W.

    Kevin W. Registered User
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    I have had two instances i had to move the eccentric. Its not something i enjoy doing, thankfully its rare that one has to do it.
     
  12. KurtinSA

    KurtinSA Registered User
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    I put the plate on a piece of plywood with some painter's tape protecting the side next to the plywood. I used some push-pins through holes in the plate to restrain it from moving. After a day or so of Kroil, I was able to turn the eccentric a skosh CCW. I used one of my screwdrivers (turned out to be my 90-degree flat blade) along with downward pressure to keep the blade in the slot. When reassembled, I had a lock situation with a pallet hitting the end of a tooth. Amazing how such a small change had that kind of result! Repeated the procedure to go back to the other direction half-a-skosh. Things looked better in terms of the drops.

    I reassembled and got the clock running. But now it looks like the exit pallet is scraping/touching the back side of the escape wheel tooth. That seems to lock the clock. Is the remedy to just shorten the exit pallet? I realize that will change the locks which seem OK now. It only really needs a small change to clear the backside of the tooth.

    Kurt
     
  13. Wayne A

    Wayne A Registered User
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    Kroil gets it done again. Yea shorten ether one but I prefer to make them even to keep the pin centered vertically between the drops.
     
  14. KurtinSA

    KurtinSA Registered User
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    Another conundrum...OK, so it appears that the exit pallet is hitting the backside of the escape wheel as it turns, stopping the clock. It would seem that the "simple" thing to do is shorten the exit pallet. However, isn't it a basic assumption that if you want to affect something on the exit pallet, the entrance pallet needs to be adjusted.

    In my current situation, the length of exposed pallets on the entrance side is slightly less, say 0.1mm than the exit pallet. The anchor pin points essentially straight up, probably due to the fact that the pin might be bent by someone in the past. So, if I'm to shorten the entrance pallet, won't that exacerbate the issue with the anchor pin orientation? Will shortening the entrance pallet have the effect I want on the exit side?

    I understand that the pallets line on a larger circle, so it would almost seem that it doesn't matter which one I change. Just visually, I would think shortening the exit pallet keeps it from contacting the backside of the escape wheel and might actually help with the orientation of the anchor pin.

    How confused do I seem! :???:

    Kurt
     
  15. Wayne A

    Wayne A Registered User
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    Adjusting ether pallet results in the same affect apart from pin centering. So if ones already longer that's the one I would shorten. Don't take much to make a difference say tenth a mm .

    I've found pallets that were half as long as the other, for these I like to match them up for the pin centering. Because finding little things like this not right would bug me to not fix..
     
  16. KurtinSA

    KurtinSA Registered User
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    Thx. That's what I'll try.

    Kurt
     

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